White Meat Report


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A report on the negative side of white meat from the Vegetarian and Vegan Foundation

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White Meat Report

  1. 1. The health consequences of consuming chicken, turkey, duck and goose meat A scientific report by Amanda Woodvine, BSc Nutrition Senior Nutritionist, Vegetarian & Vegan Foundation (VVF)
  2. 2. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat The health consequences of consuming chicken, turkey, duck and goose meat A scientific report by Amanda Woodvine, BSc Nutrition Senior Nutritionist, Vegetarian & Vegan Foundation (VVF) Published by: Vegetarian & Vegan Foundation, Top Suite, 8 York Court, Wilder Street, Bristol BS2 8QH T: 0117 970 5190 E: info@vegetarian.org.uk W: www.vegetarian.org.uk © Vegetarian & Vegan Foundation 2009 Registered charity 1037486 Graphic design: The Ethical Graphic Design Company Ltd “Humans become part of chickens’ lives billions of times a day in the most intimate way possible. We eat them. We consume their bodies. They become part of us, flesh of our flesh.” Hattie Ellis, author of Planet Chicken: The Shameful Story of the Bird on Your Plate. 2
  3. 3. CONTENTS White Meat and Pro-oxidant Damage 25 EXECUTIVE SUMMARY 5 White Meat in the Heat 26 INTRODUCTION 6 Advanced Glycoxidation End-products (AGEs) 26 Table 1: Average Intake, per Person, per Week of Heterocyclic Amines (HCAs) 27 Selected Meat and Meat Products 6 Polycyclic Aromatic Hydrocarbons (PAHs) 29 Cardiovascular Disease (CVD) 29 PART 1: WHITE MEAT – NUTRITIONAL The Role of Atherosclerosis in Coronary Heart CONSIDERATIONS 7 Disease 29 White Meat: the Low-fat Choice? 7 White Meat Consumption and Cardiovascular Table 2: Fat/Protein Content of Various Meats 7 Disease Risk 30 Table 3: Percentage Contribution of Food Types Dr Dean Ornish 31 to Average Daily Total Fat Intakes in the Dr Caldwell Esselstyn 32 Diet of Adults Aged 19 to 64 Years 8 The Effect of White Meat on Cholesterol 32 Figure 1: Meat Consumption, 1942 to 2000. The Effect of Animal Protein on Cholesterol: Data from National Food Survey 9 The China Study 34 Saturated Fat 9 The Effect of White Meat on Blood Pressure 34 Figure 2: The Percentages of Saturated Fat in Diabetes 36 Different Kinds of Fat 10 Kidney Stones & Kidney Disease 37 Table 4: Percentage Contribution of Food Types Gallstones 38 to Average Daily Total Saturated Fat Intakes in Rheumatoid Arthritis 39 the Diet of Adults Aged 19 to 64 Years 10 The Acidifying Effects of White Meat 41 White Meat: A Superfood? 11 Osteoporosis 42 White Meat as a Source of Protein 12 Table 5: Potential Renal Acid Load (PRAL) of Protein Quality 12 Selected Food Groups 43 Origins of the Protein Gap 13 Overweight & Obesity 45 White Meat: Essential for Growing Children? 14 Don’t go against the Grain 14 The Hazards of Protein Over-consumption 15 High Protein Diets for Weight Loss 15 White Meat: Desirable for Athletes? 16 PART 2: THE HEALTH CONSEQUENCES OF CONSUMING WHITE MEAT 18 Food Poisoning 18 Campylobacter 19 Salmonella 20 E. coli 20 Avoiding Food Poisoning 20 Cancer 21 Breast Cancer 22 Colorectal Cancer (Bowel Cancer) 23 Prostate Cancer 24 Other Cancers 24 3
  4. 4. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat PART 3: THE RISE IN POPULARITY OF PART 4: FROM THE EGG TO THE PLATE 50 WHITE MEAT 47 Intensive Farming or ‘Factory Farming’ 50 The Origins of Poultry Farming 47 Selective Breeding 51 Chickens 47 Nesting 51 Turkeys 48 Hatching 51 Ducks 48 Inside the… 51 Geese 49 …Broiler Shed 51 ...Turkey Shed 53 ...Duck Shed 54 Geese 55 Broiler Feed 55 Genetically Modified (GM) Feed 56 The Effects of GM Animal Feed 56 Broiler Disease and Mortality 57 Antibiotics 57 Extensive and Organic Farming 59 From the Farm to the Plate 60 Processed Poultry 60 Mechanically Recovered Meat (MRM) 61 Chicken Nuggets 62 The Environmental Impact of White Meat Production 62 CONCLUSION 63 REFERENCES 64 4
  5. 5. Executive Summary White meat – from chickens, turkeys, ducks and geese – has become the meat of choice for many people living in the West. The average consumer will eat at least 1,226 birds in a lifetime. Of all types of meat, chicken is especially popular, accounting for one third of all meat consumed in the UK. Recent fears over bird flu, food poisoning, dubious foreign imports and chicken meat pumped up with beef protein and water knocked sales a bit, but the birds’ ‘healthy’ image remains largely untarnished. White meat is perceived to be a low-fat food; something to be eaten in quantity by top athletes. However, modern farming’s focus on high-energy feed, little exercise and breeding for rapid weight gain means that even organic meat is not even close to being low-fat – even after removing the skin and scraping away the subcutaneous fat. A medium-sized chicken contains almost a pint of fat! And contrary to popular opinion, animal protein is not essential for building muscle or for children’s growth. Turkey has even been called a ‘superfood’. However, white meat contains no fibre, complex carbohydrates, nor vitamin C. When white meat takes the place of fruits, vegetables, wholegrains and pulses in the diet, the result is less vitamins, fibre, and unwanted dietary fat and cholesterol – increasing the risk of a number of chronic diseases, which are discussed in this report. In the UK, 95 per cent of chickens, 95 per cent of ducks, and the overwhelming majority of turkeys are raised on large factory farms. Crowded together indoors, these animals eat, breathe and excrete in the same physical space every day. The overcrowded, unsanitary conditions mean that infectious illnesses spread rapidly through the birds. Death rates of five to 15 per cent of all birds are common on intensive units – they fail to live to even their very young slaughter age. The amount of meat that the world eats is expected to rise by over 55 per cent in the next 20 years. Chickens, as the most intensively farmed animals, are expected to be on the front line of this change. Human health – and the environment – will be on the front line, too. 5
  6. 6. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat Introduction White meat – from chickens, turkeys, ducks and geese – has become the most popular meat for people living in the West. Apart from the muscle, other parts of the bird – collectively described as offal – are also consumed. These include the liver, kidneys, brain and pancreas (sweetbreads). In the EU, the consumption of white meat overtook that of beef and veal in 1996, when BSE hit the headlines. Britons eat almost twice as much white meat as beef every year. The average consumer will eat at least 1,226 birds in their lifetime (Viva!, 2005a). Recent fears over bird flu, food poisoning, dubious foreign imports and chicken meat pumped up with beef protein and water knocked sales a bit, but the birds’ ‘healthy’ image remains largely untarnished. It is perceived to be low in fat and something to be eaten in quantity by top athletes. The amount of meat the world eats is expected to rise by over 55 per cent in the next 20 years. Chickens, as the most intensively farmed animals, will be on the front line of this change (Ellis, 2007). Table 1: Average Intake, per Person, per Week of Selected Meat and Meat Products Average intake, per person, per week in grams (based on household purchase data) 2003-04 2006 % change since 2003-04 Poultry (cooked or uncooked) 248 255 +5.7 Fish 156 170 +9.1 Bacon and ham (cooked or uncooked) 117 111 -1.0 Meat based ready meals and convenience meat products 155 146 -6.1 All other meat and meat products 316 292 -2.8 Data from Defra, 2008a 6
  7. 7. PART 1: White Meat – Nutritional Considerations White Meat: the Low-Fat Choice? White meat is perceived, and often promoted by producers, to be a low-fat, healthy food. The reality is that it is not even close to being so. All meats are muscles, which are made of protein and fat (PCRM, 2000). Average raw chicken meat is 17.5 per cent fat – rising to 38.1 per cent once the meat is roasted (see Table 2). Raw turkey comes close at 13.7 per cent of calories from fat. Nearly half of the calories in roasted duck come from fat – and that is only if the skin and excess fat is discarded from the carcass. If this is not done then 80 per cent of the calories from roasted duck will be from fat! Roasted goose is not far behind, at 63 per cent of calories. This is in stark contrast to the one per cent fat in a baked potato, and four per cent found in baked beans. Table 2: Fat/Protein Content of Various Meats Meat Energy Fat % kilocalories Protein (kilocalories (per 100g) from fat (per 100g) per 100g) Chicken Meat, average, raw 108 2.1 17.5 22.3 Meat, average, roasted 177 7.5 38.1 27.3 Turkey Meat, average, raw 105 1.6 13.7 22.6 Meat, average, roasted 166 4.6 24.9 31.2 Light meat, roasted 153 2.0 11.8 33.7 Dark meat, roasted 177 6.6 33.6 29.4 Duck Meat, average, raw 137 6.5 42.7 19.7 Crispy, Chinese style 331 24.2 65.8 27.9 Roasted, meat only 195 10.4 48.0 25.3 Meat, fat and skin 423 38.1 81.1 20.0 Goose Roasted, meat, fat and skin 301 21.2 63.4 27.5 Pork Lean, average, raw 123 4.0 29.3 21.8 Lean and fat leg roasted 215 15.2 63.6 19.0 Lamb Lean, average, raw 153 8.3 48.8 20.2 Lean and fat, leg roasted 187 13.0 62.6 29.7 Beef Lean, average, raw 129 5.1 35.6 22.5 Adapted from Meat, Poultry and Game Supplement to McCance & Widdowson’s The Composition of Foods, 2002 (Chan et al., 1996). 7
  8. 8. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat Table 3: Percentage Contribution of Food Types to In fact, meat and meat products, including chicken Average Daily Total Fat Intakes in the Diet of Adults Aged and turkey in all their guises, are the leading source 19 to 64 Years (The National Diet & Nutrition Survey, 2003) of fat in the British diet (see Table 3), including equally unhealthy trans fats (The National Diet & Source of total fat % contribution to Nutrition Survey, 2003). Not only are we eating total fat intake meat in unprecedented amounts (see Figure 1) but Meat and meat products of which 23 modern farming methods have ensured that its fat Bacon and ham 2 content has doubled. Beef, veal and dishes 3 Lamb and dishes 1 Professor Michael Crawford of London Pork and dishes 1 Metropolitan University found that chicken Coated turkey and chicken 1 contains as much fat, gram for gram, as a Big Chicken, turkey and dishes 4 Mac. His team analysed chicken thigh meat from Burgers and kebabs 2 several supermarkets – even organic suppliers – Sausages 3 and found that they contain more than twice as Meat pies and pastries 4 much fat as they did back in 1940, a third more Cereals and cereal products 19 calories and a third less protein (Wang et al., of which 2004). Someone eating a 100 gram portion of Pizza 2 chicken would get 207 kilocalories from fat and White bread 2 only 64 from protein. And this wasn’t the Biscuits 3 breadcrumbed type of chicken, which has a much Buns, cakes and pastries 4 higher fat content. Milk and milk products of which 14 Whole milk 3 Even organic chickens didn’t do much better Semi-skimmed milk 3 nutritionally – 154 kilocalories from fat and 74 Cheese (including cottage cheese) 6 from protein – probably because despite having Fat spreads of which 12 more space than factory-farmed chickens, they’re Butter 4 on the same regime of high-energy feed, little Margarines 1 exercise and breeding for rapid weight gain. Says Reduced fat spreads (60-80% fat) 5 Professor Crawford: “This focus on rapid growth Low-fat spreads (40% fat or less) 1 has changed the lipid (fat) composition of the Potatoes and savoury snacks 10 chicken meat itself, and you cannot escape that – of which even by removing the skin and scraping away the Chips 5 subcutaneous fat stuck to the meat” (Observer, Other fried or roast potatoes 1 2005). The team also found that a medium-sized Savoury snacks 3 chicken contains almost a pint of fat! Vegetables excluding potatoes 4 (Dispatches, 2005). Fish and fish dishes 3 It should come as no surprise then, that an association has been found between meat consumption and overweight and obesity (see Overweight & Obesity, page 45) Researchers at the American Cancer Society followed more than 75,000 people for a decade to find out what it was that caused their weight loss and weight gain. High meat consumption was the food most responsible for 8
  9. 9. Figure 1: Meat Consumption, 1942 to 2000. Data from National Food Survey (Ministry of Agriculture, Fisheries and Food, 1991) Consumption of meat (UK), 1942 to 2000 1200 1000 Meat (grams per person per week) 800 600 400 200 0 1942 1947 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 Year them putting on weight (Kahn et al., 1997). Whether men or women, if they had more than a single serving of meat a day, they showed a 50 per cent increase in ‘abdominal obesity’ – they put on the pounds around their middles. From the 1980s onwards, it became common for butchers and processors to trim from meat any visible fat as part of the demand for leaner meat. It didn’t have much effect as people’s fat intake from meat has dropped by a mere five per cent since 1983 (The National Diet & Nutrition Survey, 2003; Geissler and Powers, 2005). Saturated Fat Our bodies can’t function without some fat, but it’s the right kind that’s important. We have no nutritional need for saturated and monounsaturated fats as the body can make them. Diets high in saturated fat and calories raise blood cholesterol levels and contribute to cardiovascular disease, diabetes and some cancers (see CVD, page 29). Saturated fat has 10 times the cholesterol-raising power of dietary cholesterol (Enas et al., 2003). Table 4 shows where most saturated fat comes from – animal products, including white meat! Furthermore, foods high in saturated fat generally contain substantial amounts of dietary cholesterol (see White Meat: A Superfood?, page 11). Reducing total and saturated fat intakes could also lower the risk of breast cancer (see VVF report, One in Nine). As part of a healthy diet, the Food Standards Agency encourages people to reduce the amount of hydrogenated and saturated fat that they eat and replace them with unsaturated fats (Food Standards Agency, 2005). No more than 10 per cent (and preferably less than seven per cent) of total calorie 9
  10. 10. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat intake should come from saturated fat Table 4: Percentage Contribution of Food Types to Average (Department of Health, 1991). Daily Total Saturated Fat Intakes in the Diet of Adults Aged 19 to 64 Years (The National Diet & Nutrition Survey, 2003) Not all saturated fatty acids have the same effects. Those which raise cholesterol the most are lauric Source of saturated fat % contribution acid, myristic acid, and palmitic acid, which are to saturated found in meat, dairy products, eggs and tropical fat intake oils. These three fatty acids account for 60 to 70 Milk and milk products, of which 24 per cent of the saturated fat in Western diets. Whole milk 4 Palmitic acid is the most common fatty acid in the Semi-skimmed milk 5 human diet. It is the main saturated fatty acid in Cheese (including cottage cheese) 10 animal fats (including poultry, red meats and eggs) Meat and meat products, of which 22 and in palm oil. Bacon and ham 2 Beef, veal and dishes 4 Figure 2 shows the percentages of saturated fat in Lamb and dishes 1 different kinds of fat. Around a third of the fat in Pork and dishes 1 both chicken and turkey is saturated fat. Coated turkey and chicken 1 Chicken, turkey and dishes 3 Figure 2: The Percentages of Saturated Fat in Different Burgers and kebabs 2 Kinds of Fat Sausages 3 Animal fats: Vegetable oils: Tropical oils: Meat pies and pastries 4 Beef tallow 50% Cottonseed oil 26% Coconut oil 87% Other 1 Pork fat (lard) 39% Peanut oil 17% Palm kernel oil 82% Cereals and cereal products, 18 Chicken fat 30% Corn oil 13% Palm oil 49% of which Turkey fat 30% Olive oil 13% Soybean oil 15% Pizza 2 Rapeseed oil 7% Sesame oil 14% White bread 1 Sunflower oil 10% Biscuits 4 Safflower oil 9% Buns, cakes and pastries 4 Fat spreads, of which 11 Source: Pennington J.A.T., 1994. Butter 6 Margarines 1 Polyunsaturated reduced fat 1 spreads (60-80%) Other reduced fat spreads 2 (60-80% fat) Low-fat spreads (40% fat or less) 1 Potatoes and savoury snacks, 7 of which Chips 3 Other fried or roast potatoes 1 Savoury snacks 3 Chocolate confectionery 5 10
  11. 11. White Meat: A Superfood? Amazingly, turkey is listed as a superfood in Dr Steven Pratt’s book, Superfoods: 14 Foods that Will Change Your Life. Turkey makes the top 14, along with tomatoes, broccoli, beans, blueberries, tea, oats, pumpkin, yoghurt, walnuts, spinach, salmon, soya and oranges. Dr Pratt favours turkey because it is the ‘leanest meat source of protein’. However, Dr Pratt adds several provisos to this stance. Readers are advised to eat skinless breast meat only, no more than three to four servings a week, don’t buy self-basting birds as they may contain damaging ‘partially hydrogenated oils’ and only eat ground turkey that’s labelled 99 per cent fat free! Even those who have the discipline to stick to the 3-4 ounce cautionary portion limit – about the size of a pack of cards – will be ingesting 100 milligrams of cholesterol with each portion – the same as in beef – along with a scattering of harmful trans fatty acids. The cholesterol from white meat does just as good a job at clogging arteries and causing heart disease. The human body produces cholesterol on its own and never needs outside sources. Each added dose contributes to artery blockages, leading to heart attacks, strokes, and other serious problems (see CVD, page 29). All plant foods are cholesterol-free. While metaphorically patting turkey protein on the back with one hand, Dr Pratt assassinates it with the other, cautioning against too much animal protein. Excess can lead to a loss of calcium and an increased risk of osteoporosis, kidney damage, raised blood cholesterol levels, heart disease and increased production of the hormone insulin-like growth factor (IGF-1) – which is thought to boost the growth of cancer cells (see The Hazards of Protein Over-consumption, page 15). What’s enough? A meagre 45 to 55.5 grams a day (Department of Health, 1991) and you don’t need to eat any meat to achieve it, there’s plenty in plant foods. Despite these hazards, Dr Pratt’s support for white meat is based on it containing some vitamins and minerals, such as niacin, vitamins B6 and B12, iron, selenium and zinc. But it certainly has no monopoly on them. Mixed nuts, cereal grains, yeast extracts, vegetables and fruits are useful sources of these nutrients but without the potential for harmful side effects. It’s even been shown that B12 in fortified foods such as breakfast cereals is more easily absorbed than B12 in meat, poultry and fish – particularly for the elderly. The National Academy of Sciences in the US advises adults aged 50 and over to obtain most of their B12 from fortified foods. It’s pretty good advice for younger adults as well (Tucker et al., 2000). This begs the question: what is not found in white meat? White meat contains no fibre, complex carbohydrates, nor vitamin C. Fibre cleanses the digestive tract, keeping bowels healthy and regular; slows the absorption of sugar and fat; carries away excess hormones from the blood; and lowers cholesterol. Complex carbohydrates, found only in plants, are relatively low in calories and boost metabolism. Vitamin C is an antioxidant, and is involved in immunity, wound healing and the formation of collagen in skin, tendons and bones. When white meat takes the place of fruits, vegetables, wholegrains and pulses (peas, all types of beans and lentils) in your diet, you get less vitamins, less fibre, and unwanted dietary fat and cholesterol. 11
  12. 12. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat White Meat as a Source of Protein Protein Quality Protein plays an important role in the body, forming the basis of muscles, hair, nails and collagen (the connective tissue that holds the body together). It also plays regulatory roles, causing heart muscle to contract and the body to digest food, and is what makes DNA and enzymes. To make protein, plants combine sugars (which they make from sunlight, carbon dioxide and water) with nitrogen from the air or soil. The end products are protein building blocks called amino acids – ‘amino’ simply means nitrogen-containing. There are 20 or so different amino acids in the body, of which the body can make about 11 just from carbohydrate, fat and nitrogen (from protein) in your diet. About nine of the amino acids are called ‘essential amino acids’ that must be supplied in the diet as the body cannot make them. The essential amino acids in humans are:  Histidine (in children)  Isoleucine  Leucine  Lysine  Methionine  Phenylalanine  Threonine  Tryptophan  Valine Animal, soya and quinoa (an increasingly popular food, which is a seed, used as a grain) products are sometimes called complete proteins as they contain plenty of all of the essential amino acids. Many other plant proteins have a relatively low amount of one or more of the essential amino acids – the so- called ‘limiting’ amino acid. Pulses (peas, beans and lentils) are a major exception to this general rule and contain good amounts of high quality protein. Nuts and seeds are rich protein sources, too. However, the concept of a limiting amino acid has limited practical relevance – especially for people in affluent countries. Human protein requirements are relatively low compared to other species. Many dietary staples provide enough protein to meet these relatively low human needs. In addition, affluent people eat diets containing mixtures of several different proteins, rather than single proteins. Different proteins consumed over a period of time have differing limiting amino acids. This means that any deficiency of one will be compensated for by a relative surplus of that amino acid in another. This is called mutual supplementation of proteins. There is a persistent myth that vegetarians need to be well educated and choose protein foods that make up for the amino acid deficiencies of each another. But research shows that this is unnecessary, and that both vegetarians and omnivores get enough protein, including plenty of the amino acids they need, as long as they are getting enough calories. 12
  13. 13. Origins of the Protein Gap In developed countries such as the UK where meat consumption is relatively high, meat provides the main source of protein. Meats are conventionally viewed as protein foods or ‘complete proteins’, because they contain all of the essential amino acids that the body needs. However, meats are also a major source of dietary fat (see White Meat: the Low-Fat Choice?, page 7). The myth that people should eat more protein is a hardy one, which dates back to the early twentieth century. The majority view back then was that health – and especially fitness – depended on generous amounts of protein in the diet, particularly meat (Millward, 2004). It was even reckoned that world hunger and malnutrition among children in the developing world was a result of not having enough protein, especially high-quality (ie animal) protein (Autret, 1969; Gounelle de Pontanel, 1972; Stillings, 1973; Scrimshaw and Young, 1976). The myth reached epic heights in the 1960s. A UN report was published that identified worldwide protein deficiency. It called for a ‘global strategy to avert the impending protein crisis’. International aid began to focus on projects to address the so-called protein gap. The US government, for example, subsidised the production of dried milk powder to provide ‘high-quality’ protein for the world’s poor (Campbell and Campbell, 2005). Then came a report by the Royal College of Physicians on diet and heart disease in 1976, which encouraged people to eat white meat in place of red, on the grounds that it contains less saturated fat and is therefore less damaging (Wang et al., 2004). It certainly worked, with poultry consumption in the UK almost trebling from the 1960s, with sales of pork, lamb and beef declining. However the protein gap actually disappeared ‘at the stroke of a pen’ in 1969, when Miller and Payne concluded that almost all dietary staples contain sufficient protein to meet human needs. They calculated that even diets based on staples that were very low in protein were unlikely to be specifically protein deficient (Miller and Payne, 1969). In the decades since 1969 this view has become the nutritional consensus. The maximum protein required, according to leading health bodies such as the World Health Organisation (WHO), is only around eight per cent of our calories from protein. Most foods can provide us with this eight per cent. The foods that are exceptions to this include fruits (which contain about five per cent of their energy from protein) and many sweets and junk foods. The WHO’s value includes a large safety margin, so most people’s real needs are even lower. Scientists also once believed that some ‘complete’ protein was needed at each meal. We now know that the amino acids from protein remain in our bodies for at least four hours and for as long as 48 hours. Despite this revolutionary change of mind, the greatly reduced emphasis on protein in human nutrition has been slow to filter through beyond the ranks of specialists. 13
  14. 14. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat White Meat: Essential for Growing Children? There is a persistent myth that meat (as a protein food) is essential for growing children – perhaps more so than for adults. In reality, current protein reference nutrient intakes (RNIs) suggest that children can manage on a lower minimum concentration of protein in their diets than adults. A two-year-old child requires almost three times as many calories (energy) as an adult on a weight-for-weight basis, but only about one-and-a-half times as much protein. This means that a child’s increased need for energy is far greater than their need for more protein per se. This applies to children of all ages: their increased calorie needs cancel out or, in most cases, greatly exceed, their increased need for protein. The main cause of death in children in developing countries is from something called protein-energy malnutrition. It usually develops in children who get too little protein and energy, and these deficiencies tend to go hand-in-hand. Diets that contain enough energy (kilocalories) typically contain plenty of protein (see Origins of the Protein Gap, page 13), so the real problem is usually quantity, rather than quality of food. Wartime studies in the UK by Widdowson and McCance found that orphanage children grew faster than the general population when they ate a bread-based diet, with only a small fraction (14 per cent) of their protein coming from milk products. The orphanage children grew no faster when nearly half of their protein was from milk! Bread provided the children with plenty of energy to support their growth, whilst meeting more than double their protein needs (Millward, 2004). Why were early estimates of protein requirements in children inflated? Dr Geoffrey Webb, Senior Lecturer in Nutrition and Physiology at the University of East London suggests that inappropriately extrapolating data from animal experiments to humans may have been a factor (Webb, 1995). Primates – including humans – have slower growth rates than most animals, and much lower rates than most common laboratory animals. Says Webb: “The relative protein requirements of these rapidly growing species [laboratory animals] are likely to be higher than those of human infants and children.” Don’t go Against the Grain Grains supply the vast majority of the calories that the world eats, and they provide protein, too – even though most people equate protein with animal foods such as meat, fish or dairy. In fact, almost all foods – grains, pulses (peas, all types of beans and lentils), nuts, seeds and vegetables – contain protein. It’s relatively easy to consume enough protein if you’re a vegetarian, and especially so if you select from two or more of these three groups in a given day: wholegrains; pulses; nuts and seeds. Says Dr Linda Bacon, nutrition lecturer at City College of San Francisco: “Eat a varied, nutrient-dense diet and there is no need to go out of your way to get protein or specific amino acids or amino acid combinations. It is more important to pay attention to the other nutrients the protein is packaged with than to concentrate on the protein itself. (For example, is the food high in fibre or low in saturated fat?) “Plant products will typically do a better job of meeting your protein needs than animal products, both because they are less concentrated sources of protein (making protein over-consumption less 14
  15. 15. likely) and because they are more likely to be bundled with other great nutrients, such as fibre, vitamins, minerals, phytochemicals and healthy fats,” (Bacon, 2005). The Hazards of Protein Over-consumption The average Westerner gets well in excess of their protein needs. British men eat on average 88.2 grams per day, and women 63.7 grams (The National Diet & Nutrition Survey, 2003). This means that both sexes get more than double (just over 16 per cent) the WHO’s recommendation of around eight per cent calories from protein – and suggests that protein deficiency is highly improbable in Britain and other industrialised countries. An average portion of chicken meat (100g/3.5oz) provides 22.3g of protein, and turkey meat 22.6g – roughly half of a woman’s daily requirement and almost half a man’s. Duck and goose meat provide 19.7g and 27.5g of protein respectively. Too much protein has a well-documented link with many diseases, including kidney disease, osteoporosis, cancer, type 2 diabetes, and cardiovascular disease. High protein diets usually involve eating protein from concentrated sources, such as animal products. As discussed in Saturated Fat, page 9, animal products, even lean-looking meats, are often associated with large amounts of saturated fat and cholesterol. They also tend to be high in oxidants (see White Meat and Pro-oxidant Damage, page 25), and low in fibre and antioxidants. But putting these nasties aside, there is strong evidence to suggest that it is excess protein per se which plays a part in increasing disease risk. According to Dr Bacon, some amino acids may promote disease while others enhance health. There is compelling evidence that animal proteins – independent of other associated nutrients – increase risk for cancer (O’Keefe et al., 1999; Sieri et al., 2002; Holmes et al., 2003; Yang et al., 2002), atherosclerosis (Campbell, Parpia and Chen, 1998; Campbell and Junshi, 1994), osteoporosis (Messina and Messina, 2000; Hu et al., 1993) and type 2 diabetes (Song et al., 2004). This was particularly evident in the China Project (Campbell, Parpia and Chen, 1998; Campbell and Junshi, 1994; Campbell and Campbell, 2005). The Project was one of the largest and most comprehensive studies ever undertaken to examine the relationship between diet and disease. Huge differences were seen in disease rates based on the amount of plant foods participants ate compared to animal foods. High-Protein Diets for Weight Loss Data suggests that protein is the most filling nutrient of all (Eisenstein et al., 2002; Halton and Hu, 2004) and has been credited with helping to curb hunger in people following high-protein diets. However, this has not been tested objectively. Alternative explanations such as monotony and ketosis may also contribute (Mattes et al., 2005). While a few studies have observed that high-protein, carbohydrate-restricted diets can bring about modest short-term weight loss (Westman et al., 2002; Foster et al., 2003; Samaha et al., 2003) the long-term health consequences of following such diets in order to lose weight have not yet been investigated. Says Dr Steven Pratt, author of Superfoods: 14 Foods that will Change Your Life: “There’s no doubt that the leaner the protein source the better, but low-fat, healthy animal protein is very hard to find,” (Pratt and Matthews, 2004). 15
  16. 16. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat Indeed, most high-protein, low-carbohydrate diets contain less than 10 per cent carbohydrate, 25 to 35 per cent protein, and 55 to 65 per cent fat (PCRM, 2004). Because the protein is provided mainly by animal sources, these diets are high in saturated fatty acids and cholesterol, and could perhaps more aptly be renamed ‘high-fat’ diets (PCRM, 2004). 429 individuals following such a high-protein, high-fat, carbohydrate-restricted diet voluntarily logged their diet associated health problems using an online registry (www.atkinsdietalert.org). Common findings included constipation, loss of energy, bad breath, difficulty concentrating, kidney problems, and heart related problems, including heart attack, bypass surgery, arrhythmias and elevated blood cholesterol levels (PCRM, 2004). Says Dr Pratt: “Many people mistakenly believe that there’s some special ‘fat burning’ paradise that you enter when you severely restrict your carbohydrate intake and simultaneously boost your protein intake… [however] most people who follow a high-protein diet and lose weight do so simply because their food choices are such that they automatically cut down on calories. When you restrict or severely limit one group of foods (carbohydrates), a group that ordinarily comprises over half your calorie intake, you can’t help but lose weight. And once you go off the diet, all or most of the weight usually comes back.” And Dr Pratt cautions against additional dangers with an exceptionally high protein intake: “The more protein you take in, the more calcium you excrete in your urine, thus raising your risk for osteoporosis [see The Acidifying Effects of White Meat, page 41]. In the Nurses’ Health Study, women consuming more than 95 grams of protein a day (an extra-lean 6-ounce [170 gram] hamburger has 48.6 grams of protein) had an increased risk of fractures. While there is ongoing debate on this subject, it seems that vegetable protein causes less bone loss than animal protein.” Too much protein also puts a strain on the kidneys, forcing them to expel extra nitrogen in the urine, increasing the risk for kidney disease (also see Kidney Stones & Kidney Disease, page 37). White Meat: Desirable for Athletes? Contrary to popular opinion, protein is not essential for building muscle. The belief that eating animal muscle (ie meat) means you automatically build human muscle simply isn’t true. Muscles develop by being used, rather than eating greater amounts of another animal’s flesh. Gorillas are the most muscular of all the primates. Their impressive physique comes from regular physical activity and a 99.9 per cent plant diet (0.1 per cent insects) (Fossey, 1977). There is a widely held belief amongst athletes and coaches that training increases protein requirements. This also remains contentious. While the requirements for certain water-soluble vitamins, protein and iron may be slightly increased (Webb, 2006) these should be more than offset by an increased total food intake during training. This is the case for most athletes who are not deliberately and severely restricting their energy intake (Webb, 2006). Athletes in training expend significantly more energy than the average person. As long as they eat 16
  17. 17. enough to satisfy their appetite and to maintain a constant body weight, they should automatically consume more calories than the average person. If their diet is similar in nutrient density to that of the rest of the population, then they should also take in more essential nutrients than the average person. This increased total food intake therefore makes protein – or any other nutrient – inadequacy unlikely in athletes. Of course some athletes – such as gymnasts, figure skaters, jockeys, and those involved in sports where athletes are divided into weight categories – perceive the need to be lean, and thus restrict their energy intake. They have much lower energy intakes than would be predicted from their activity levels. It is therefore possible that they might have insufficient nutrient intakes. For a discussion of the nutritional consequences of eating processed meat, see Processed Poultry, page 60. 17
  18. 18. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat PART 2: The Health Consequences of Consuming White Meat Food Poisoning According to the Food Standards Agency, an estimated 5.5 million people in the UK are affected by food poisoning each year. Most cases aren’t reported because people have mild symptoms and recover quickly. As a result, less than 100,000 cases a year are tested for the exact cause of food poisoning (NHS, 2009a). Symptoms of food poisoning are generally the same, regardless of the bug – abdominal cramps, nausea, vomiting, diarrhoea, stomach pain, and sometimes fever – and may occur within 30 minutes of consuming contaminated food. Although food poisoning is particularly serious for children, adults can also be affected. Patients become dehydrated, and for those who are already vulnerable – babies, the elderly, people with weakened immune systems and pregnant women – the resulting disturbance in their body chemistry can sometimes cause more serious illness, organ failure or even death. Many cases of food poisoning are caused by micro-organisms, including bacteria, viruses and moulds. Food poisoning from bacteria occurs in different ways. Some types of bacteria release toxins while they are growing in food, which cause food-poisoning symptoms soon after the food is eaten. With other types of food poisoning, the bacteria grow in the body first before causing symptoms. This leaves a gap between eating and symptoms called the incubation period. The incubation period varies in length – it can be a few hours or up to a few days. A relatively small number of types of bacteria are responsible for almost all the serious food poisoning in the UK. BUPA (2008) lists the food sources of food poisoning bacteria as:  meat and meat products – such as minced meat and pâtés  poultry – such as chicken or turkey  seafood – fish and shellfish  eggs and raw egg products (such as mayonnaise)  unpasteurised milk (or milk contaminated after pasteurisation)  soft and mould-ripened cheeses  cooked foods – such as fried rice In fact, 95 per cent of food poisoning is caused by animal products – either directly or through their contamination of other foods (Goldman, 2001). Chicken is the main source of food poisoning in Europe. In recent years, the amount of chicken eaten in the UK has risen dramatically, so it is not surprising that food poisoning is on the increase. The conditions in which broiler chickens are kept are rife for the spread of disease (see Inside the Broiler Shed, page 51). Thousands are kept per shed, in tightly confined spaces, and the birds are not 18
  19. 19. cleaned out during their six week lives. Not only do they live in their own excreta, they also live on top of the chickens that die in the factory-farming process. Bacteria may be introduced to chicken flocks from outside the sheds, transmitted from parent to offspring (eg through eggs, in the case of Salmonella), or simply remain in inadequately cleaned poultry sheds. Pathogens such as E. coli O157 and Campylobacter are picked up by broilers on farms and excreted in high numbers in the faeces of infected chickens. As chickens eat faeces, pathogens spread easily in broiler chicken flocks – without necessarily causing illness in the birds themselves. E. coli O157 may be a particular threat, as infected animals may show no symptoms of disease but still be infected, and thus excrete large numbers of the pathogen (Food Standards Agency, 2008c). Pathogens are often spread further at slaughter. Traditionally, animal manure has been used as a fertiliser (along with certain wastes from abattoirs, such as gut contents and blood). This means that bacteria, parasites and viruses may directly contaminate fertilised crops and the livestock eating them, or, more indirectly, may contaminate water sources. Just picking up a package of meat in a supermarket could put someone at risk of food poisoning. Researchers swabbed the outside surface of packages of raw meat – and found Salmonella, Campylobacter and multidrug-resistant E. coli present (Burgess, 2005). Poultry showed most contamination, followed by lamb, pork and beef. One swab of a single Q-tip picked up over 10,000 live E. coli bacteria – and just 10 E. coli 0157:H7 bacteria can lead to a potentially fatal infection (CAST, 1994). The researchers conclude: “The external packaging of raw meats is a vehicle for potential cross-contamination by Campylobacter, Salmonella, and E. coli in retail premises and consumers’ homes,” (Burgess, 2005). Campylobacter Like Salmonella and E. coli, Campylobacter are bacteria found in the intestines of many animals, non- organic and organic, although most commonly in poultry (Newell and Fearnley, 2003). Chicken is the largest single source of Campylobacter poisoning. Infection of an entire flock will usually take just a few days. It is more common in free-range and organic birds because Campylobacter is widespread in the environment (Newell and Fearnley, 2003). The bacterium causes severe abdominal pain and, often, bloody diarrhoea. Rare but serious long-term effects can develop, such as Reiter’s Syndrome, a type of arthritis. An estimated one in a thousand people infected with Campylobacter go on to suffer Guillain-Barré Syndrome, a neurological condition that can be fatal (Ellis, 2007). Campylobacter is a common finding in chickens on supermarket shelves. A series of Food Standards Agency surveys between 2001 and 2004 showed that between 42 per cent and 76 per cent of retail chickens were contaminated with Campylobacter depending on the region. The highest rate was found in Northern Ireland and the lowest in Wales. 19
  20. 20. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat Salmonella There are 2,000 different types of Salmonella bacteria and the intestines of chicken act like a reservoir and provide the potential for the spread of bacteria. According to a Government survey, organic laying hen farms seem to have a lower level of Salmonella than caged hens. The study showed that 23.4 per cent of farms with caged hens tested positive for Salmonella compared to 4.4 per cent in organic flocks and 6.5 per cent in free-range flocks (The Veterinary Record, 2007). Salmonella poisoning can cause vomiting, diarrhoea, abdominal pain, and fever lasting for several days. When it spreads to the blood and other organs, it can be fatal. A recent Food Standards Agency survey of retail chicken showed that about six per cent of chickens were contaminated with Salmonella. Salmonella cause between 50 and 100 deaths in the UK every year. E. coli As with Campylobacter and Salmonella, the presence of E. coli in undercooked food is a sign of faecal contamination – from the meat, dairy and egg industries (Schoenl and Doyle, 1994). E. coli infection causes haemorrhagic colitis (bloody diarrhoea) and abdominal cramps. In extreme cases it can progress to kidney failure, seizures, coma and death. E. coli (0157:H7) infection – from faecal contamination – is a leading cause of acute kidney failure in children. Additionally, millions of people develop ‘extra-intestinal’ E. coli infections – urinary tract infections (UTIs), which can invade the bloodstream and cause death. UTIs are among the most common infectious diseases in women – and may well be linked to eating meat. The faecal flora found in animal carcasses (eg Campylobacter, E. coli and Salmonella) may show antibiotic resistance. This is because of antimicrobial agents used in food-animal production (see Antibiotics, page 57). Indeed, a BBC investigation in 2005 found that about half of British chickens contained antibiotic- resistant E. coli bacteria – resistant to the antibiotic Trimethaprim, used to treat UTIs. Scientists suspect that by eating chicken and other meat, women infect their lower intestinal tract with antibiotic-resistant bacteria, which can then creep up into their urethra, causing a UTI. A BBC 1 television report expressed concerns that: “these types of bacteria could make infections in humans more difficult to treat,” (ElAmin, 2005). Avoiding Food Poisoning Most bacteria grow best and increase in number in a moist environment between a temperature ‘danger’ zone of between 5°C and 60°C. Bacteria cannot grow effectively at temperatures above or below this. The Food Standards Agency advises: “It’s very important to cook meat properly to make sure that any harmful bacteria have been killed. Otherwise you might get food poisoning,” (Food Standards Agency, 2008c). Unfortunately, the temperature required to kill faecal bacteria (160ºF/71ºC) is the same temperature which produces carcinogenic compounds called heterocyclic amines (see HCAs, page 27). 20
  21. 21. If you want to avoid food poisoning, or any potential risk from bird flu, then you’re advised to cook white meat properly. But beware – thoroughly cooked chicken may increase the risk of cancer. According to Dr Michael Greger: “Although there are cooking methods that result in lower carcinogen concentrations (marinating followed by a microwaving pre-treatment and pouring off of the ‘juices’, followed by relatively low temperature frying with frequent flipping), there does not seem to be a way to cook meat to an internal temperature necessary to kill off [food poisoning] bacteria without producing at least some carcinogenic compounds. And even low doses have been shown to cause human DNA mutations which could lead to cancer,” (Greger, 2005). Cancer In 2007, around 7.6 million people worldwide died of cancer. In the UK, cancer causes 126,000 deaths per year and it kills one in four (NHS, 2009b). There are hundreds of different types of cancer. The most common cancers in Britain include cancers of the breast, prostate, lung, colon (or rectum), bladder and uterus (womb). Cancer begins as a single abnormal cell, which begins to multiply out of control. Groups of such cells form tumours and invade healthy tissue, often spreading to other parts of the body. It takes years for a noticeable tumour to develop. Substances which promote the development of cancerous cells are called carcinogens, and may come from foods, the air, or from within the body. Although most carcinogens are neutralised before damage can occur, they sometimes attack and alter the cell’s genetic material (DNA). While smoking is the biggest single preventable risk factor for cancer – causing one third of all cancers – a poor diet may be responsible for up to a third of all cancer deaths (Department of Health, 2000). Compounds known as inhibitors can help prevent abnormal cells from growing. These include carotenoids, the pigment that gives fruits and vegetables their colour; flavones and indoles found in vegetables such as cabbage, broccoli and Brussels sprouts; and beta-carotene, in dark green and yellow vegetables. According to the World Health Organisation, fruit and vegetables offer protection from lung, colon, bladder, rectum, oral cavity, stomach, cervix and oesophagus cancers. Dietary fat, on the other hand, is a known promoter, helping abnormal cells to grow quickly. Research suggests that fat in foods increases a person’s risk for cancer, and it may also adversely affect breast cancer survival rates for those who have cancer (Wynder et al., 1986). There is evidence that animal fat is much more harmful than vegetable fat. A diet rich in saturated animal fats, cholesterol, animal protein, sugar, salt and processed foods has been shown to increase the risk of certain cancers – specifically cancers of the bowel, stomach, mouth, larynx, and oesophagus. However, a poor diet can also increase the risk of many other cancers including breast and prostate cancer (Cancer Research UK, 2005a). As long ago as 1892, Scientific American stated that: “Cancer is most frequent among those branches of the human race where carnivorous habits prevail,” (PCRM, 2008a). 21
  22. 22. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat Breast Cancer In the UK, breast cancer is the most common type of cancer among women. In 1980 there were 25,000 cases each year. Nowadays approximately 45,000 new cases of breast cancer are diagnosed annually. It usually affects women who are over 50 years of age and who have reached the menopause. However, it is possible for women of any age to be affected by breast cancer and, in rare cases, the condition can also affect men (NHS, 2009c). Although Asian countries have a much lower rate of breast cancer than Western countries, when Japanese girls are raised on Western diets, their rate of breast cancer increases dramatically (PCRM, 2008). A Japanese study found the risk of breast cancer was eight-and-a-half times higher in affluent women consuming meat every day than poorer women who did not eat meat daily (Hirayama, 1978). One proposed reason is that high-fat foods – such as meat, dairy products, fried foods and vegetable oils – cause women to make more oestrogens. These encourage cancer cell growth in the breast and other organs which are sensitive to female sex hormones. It is believed that switching to a lower fat diet throughout life decreases the risk of hormone-related cancer. Research in the Journal of the National Cancer Institute found that when girls aged eight to ten reduced the amount of fat in their diet – even very slightly – by increasing fruits, vegetables, grains and pulses, and cutting down on animal-derived foods – their oestrogen levels were at lower and safer levels for the next few years. The amount of oestradiol (a main oestrogen) in their blood dropped by 30 per cent, compared to a group of girls who did not change their diets (Dorgan et al., 2003). In addition, researchers at the Ontario Cancer Institute conducted a meta-analysis of all the case- control and cohort studies published up to July 2003 which looked at how dietary fat and fatty foods affect breast cancer risk. A high total fat intake was associated with increased breast cancer risk. Furthermore, a high meat intake increased cancer risk by 17 per cent, and a high saturated fat intake increased cancer risk by 19 per cent (Boyd et al., 2003). Several studies show links between meat intake and breast cancer risk, even when confounding factors, such as total energy (calorie) intake and total fat intake are controlled (De Stefani et al., 1997; Matos et al., 1991). Part of the reason may be that meat is a source of carcinogens such as HCAs, formed when meat is cooked at high temperatures (see HCAs, page 27). Certain HCAs reach the mammary gland (Snyderwine et al., 1994). Zheng et al. conducted a case-control study among members of the Iowa Women’s Health Study. 41,836 women were followed over the years from 1986 for mortality, cancer incidence and diet. During 1995 to 1996, Zheng and colleagues looked at all members of the original group who had been diagnosed with breast cancer (the cases) and compared them to a random sample of women from the original group who were free of cancer (the controls). They looked at the intake and preparation of meats consumed by both groups over the years. This analysis found that breast cancer risk increased with increasing intake of well done to very well done meat (Zheng et al., 1998). 22
  23. 23. Colorectal Cancer (Bowel Cancer) Colorectal cancer, or bowel cancer, refers to cancer in the colon (first part of the large intestine) and rectum (last part of the large intestine). Colon cancer affects men and women equally. However, it is the third most common type of cancer in men, and the second most common type in women. Colon cancer usually affects people over the age of 40, with the majority of people who are diagnosed with the condition being over 60 years of age. Every year, 35,000 people are diagnosed with bowel cancer in the UK (NHS, 2009d). The Harvard Nurse’s Health Study found that women with higher animal fat intakes had a greater risk of bowel cancer (Willett et al., 1990). Similar results have been found for men. One prospective study into the dietary risk factors for colorectal adenomas (precursors of cancer) found a link with saturated fat. Fibre, however, reduced risk (Giovannucci et al., 1992). Total fat and saturated fat, which tend to be considerably higher in animal products than in plant foods, and refined sugar, all increase colon cancer risk. A review of 32 case-control and 13 cohort studies concluded that meat consumption is associated with an increase in colorectal cancer risk, especially red and processed meat (Norat and Riboli, 2001). As with breast cancer, cooking methods that promote the formation of HCAs are believed to play a significant role in bowel cancer risk (Norat and Riboli, 2001). However, contrary to claims that white meat is healthier than red meat, earlier studies have also indicated that those consuming white meat, particularly chicken, have approximately a three-fold higher colon cancer risk, compared to vegetarians (Fraser, 1999). A 1998 prospective study (recording subjects’ diets and tracking their health over the following years) linked both red and white meat (and fish) intake to colon cancer. Researchers at Loma Linda University examined the eating habits of 32,000 men and women between 1976 and 1982 and monitored cancers over the six years. Among those who avoided red meat but ate white meat less than once a week, bowel cancer risk was 55 per cent higher than for those who avoided both kinds of meat. Those who had white meat at least once a week had more than a three-fold risk of suffering bowel cancer. Conversely eating pulses (peas, beans or lentils) at least twice a week was associated with 50 per cent lower risk compared to never eating these foods (Singh and Fraser, 1998). Interestingly, ‘substituters’ (people who used low-fat dairy products instead of high-fat ones; poultry instead of red meat; and wholegrains instead of refined grains) were at reduced risk for colon cancer but the reduction was not significant. The authors conclude that this was because many adopting these ‘substituter’ so-called ‘healthier’ diets were not increasing their vegetable consumption and this aspect of the diet is important in significantly reducing bowel cancer risk (Slattery et al., 1998). Fibre is a major constituent of a plant-based diet and it has been long thought that high-fibre diets 23
  24. 24. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat help to protect against colon cancer. The reason for this centres around fat digestion. In order to absorb fat, the liver makes bile, which it stores in the gallbladder. After a meal, the gallbladder sends bile acids into the intestines. Bacteria in the intestines turn these bile acids into cancer-promoting substances (mutagens) called secondary bile acids. Meats, unlike plant foods, contain a substantial amount of fat, and also nurture the growth of bacteria that cause these disease-causing acids to form. Fibre, however, changes the type of bacteria that are present in the intestine, which reduces the production of carcinogenic (cancer-causing) secondary bile acids (PCRM, 2009a). Fibre may also help both by diluting the presence of such harmful acids in the faeces and by speeding up their passage through the colon. Prostate Cancer Prostate cancer is the most common cancer in men, responsible for 25 per cent of newly diagnosed cases of cancer in England and Wales (NHS, 2008e) and the second most common cause of male cancer deaths after lung cancer. One in 14 men in the UK will be diagnosed with prostate cancer at some point in their lives (Cancer Research UK, 2005b). The chances of developing prostate cancer increase with age. Most cases develop in men aged 65 or older. For reasons that are not understood, prostate cancer is more common in men who are of Afro- Caribbean or African descent and less common in men of Asian descent. Professor Jonathan Waxman, the founder of the Prostate Cancer Charity, believes that dietary factors are strongly implicated. The rise in meat consumption since World War II is the main culprit but eating dairy products can also increase a man’s chances of developing it due to the hormones in cow’s milk. Vegetarians are half as likely to contract it as non-vegetarians (Browne, 2000). Research shows that men who consume diets based on animal products tend to have more testosterone and oestrogens compared to men who eat plant-based foods. This may be due to over-production of these hormones in the body or, since fibre in the diet is essential for the normal excretion of sex hormones, a lesser ability to get rid of them. This hormonal boost can affect the prostate and, according to the Physicians Committee for Responsible Medicine, is probably the reason for increased cancer risk among those on a meat-based diet (PCRM, 2009b). A lower risk of prostate cancer is associated with diets higher in rice, soya bean products and vegetables (PCRM, 2009b). Not surprising then that vegetarians have been found to have low rates of prostate cancer (Phillips, 1975) and increasing consumption of pulses, fruits and vegetables are all associated with significantly decreased prostate cancer risk (Mills et al., 1989). Other Cancers Although not as extensively studied as breast, colon, and prostate cancer risk, many studies have found a significant link between meat consumption and the risk of kidney and pancreatic cancer. Three of eight case-control studies examining the relationship between renal cell cancer and meat consumption found a statistically significant increase in cancer risk with high meat consumption. A Japanese study 24
  25. 25. found that people consuming meat daily had higher death rates from kidney cancer than those eating meat less frequently (World Cancer Research Fund, 1997). Pancreatic cancer is relatively uncommon, yet it is frequently fatal, with fewer than 20 per cent of patients surviving for one full year. No relationship has been demonstrated between dietary fat, saturated fat, and protein intake and pancreatic cancer risk, which implies that cooking methods, and possibly HCA and PAH formation in cooked meat, might explain the link (World Cancer Research Fund, 1997). Risk factors for pancreatic cancer were evaluated in a 20-year study between 1966 and 1986. This study of over 17,500 men in the United States revealed – after adjustment for other risk factors – that those who ate meat were three times more likely to develop cancer of the pancreas than those with low meat consumption (Zheng et al., 1993). International comparison studies have shown that as Japan’s diet has Westernised and become more reliant upon animal fat and protein, the incidence of pancreatic cancer has increased. Consumption has steadily increased from a daily level of 6.5 grams of animal fat per person in 1955 to 27.6 grams in 1987. Animal protein consumption has doubled in these 30 years (Wynder et al., 1991). A case-control study of diet and endometrial cancer published in 1993 revealed that women eating the most animal fat and animal protein had more than three times the risk of developing this particular cancer. High consumption of meat, eggs and fresh fish were all associated with elevated risk (Shu et al., 1993). White Meat and Pro-oxidant Damage A leading theory behind ageing and disease is the Oxidant Stress Theory. This theory suggests that free radicals cause both the age-related deterioration in our bodies and the tissue damage behind most chronic diseases. Put simply, ageing and disease can be thought of as the oxidation of our bodies – just like rust is the oxidation of metal. Free radicals are unstable molecules which are a product of oxidation. In stable molecules, electrons normally associate in pairs, providing a balance. Everyday functions, such as simply breathing, digesting food or moving about can remove one electron from a molecule, creating a free radical. This now unstable molecule tries to regain an electron by snatching one from another molecule. When it succeeds, another free radical is created and a chain reaction is set up in which the DNA, the body’s vital genetic information, may be damaged. The Oxidant Stress Theory explains why plant foods (fruits and vegetables, pulses (peas, beans and lentils), nuts, seeds, and wholegrains) seem to protect against numerous diseases, including Alzheimer’s, cancer and cardiovascular diseases. The antioxidants contained in these foods help to destroy the free radicals produced in our own bodies and those present in the environment. A healthy vegetarian diet made up of the aforementioned foods results in higher intakes of dietary fibre, antioxidants and protective plant nutrients known as phytochemicals (Rajaram, 2003). Higher blood levels of antioxidants, as found in vegetarians, leads to correspondingly lower rates of chronic 25
  26. 26. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat disease. Researchers in the Slovak Republic have demonstrated that vegetarians have lower levels of the intermediate indicators of oxidised tissue damage than meat eaters. The researchers gauged the levels of tissue damage in vegetarians and meat-eaters by measuring the level of something called peroxidised conjugated dienes. These are caused by the highly toxic free radical, hydroxyl. Over 40 per cent of the meat-eating subjects exceeded safety limits for these damage indicators, compared to just eight per cent of those who had followed a vegetarian diet for an average of ten years (Krajcovicová-Kudlácková et al., 2004). The researchers believe that levels of oxidant damage in vegetarians would be lower still if those in the study had not had elevated levels of homocysteine due to inadequate vitamin B12 intake. To get the full health benefits from a plant-based diet, they recommended that vegetarians ensure a reliable source of vitamin B12 (from fortified foods including breakfast cereals and reduced salt yeast extract or supplements). The results of the study: “document a better antioxidant status of vegetarians as a consequence of higher consumption of protective food.” Furthermore, the researchers suspect that the haem (blood- based) iron found in red meat, chicken and fish was a particular cause of pro-oxidant damage (Krajcovicová-Kudlácková et al., 2004). White Meat in the Heat Advanced Glycoxidation End-products (AGEs) Advanced Glycoxidation End-products (AGEs, also known as glycotoxins) are toxins, naturally produced by the body each day. Cigarette smoke is a powerful source of glycotoxins, (Cerami et al., 1997) although they are also obtained via the diet. AGEs have numerous detrimental effects on the body. They accumulate in joints and cause arthritis (Verzijl et al., 2003); they accumulate in the brain contributing to Alzheimer’s disease (Münch et al., 1998); and in arteries, causing high blood pressure (Silacci, 2002) and atherosclerosis (Stitt et al., 1997). AGEs can also build up in the eyes, causing cataracts, (Stitt, 2001); in the kidneys, contributing to kidney failure (Miyata et al., 2000); and in the penis causing male erectile dysfunction (Seftel et al., 1997). The Maillard Theory blames nearly all of the complications of ageing on the build-up of these toxic compounds (Baynes, 2002). Researchers at Mount Sinai measured the amount of AGEs in over a hundred common food items. The highest amounts were predominantly found in meat products, including oven-fried chicken, McDonalds Chicken Nuggets, and cooked chicken breast (Goldberg et al., 2004). Investigators with the Women’s Health Study reported that the AGEs in meat may be why women who eat meat five or more times a week are at significantly higher risk for developing diabetes (Song et al., 1994). Dry heat, protein and fat seem to be the combination of factors needed to produce these glycotoxins. The researchers comment: “Foods that contain mostly carbohydrates, starches, fruits, vegetables… 26
  27. 27. contain the lowest AGE concentrations.” However, at high enough temperatures, high fat and protein plant foods such as roasted nuts can also form significant amounts of AGE. The researchers propose three ways of decreasing dietary intake of AGEs. Firstly, reducing the intake of high-AGE foods such as full-fat cheeses, meats and highly processed foods. Secondly, using cooking techniques that minimise AGE formation, such as boiling, steaming and microwaving, rather than frying, roasting or grilling. Thirdly, by selecting unprocessed nutrients when possible. Centring the diet around whole plant foods which have ideally not been exposed to temperatures above about 400ºF (204ºC) is an ideal way to reduce exposure to AGEs. Heterocyclic Amines (HCAs) Heterocyclic amines, or HCAs, are a group of hazardous chemicals linked to cancer in humans. They are produced when many animal products are cooked – including chicken, beef, pork and fish. Even normal grilling, frying or roasting can produce significant quantities of HCAs (Skog et al., 1998; Robbana-Barnat et al., 1996; Thiebaud et al., 1995). The longer and hotter the meat is cooked, the more these compounds form (Knize et al., 1994). Consequently, the concentrations of HCAs in different meats can vary by more than 100-fold. In January 2005, HCAs were added to the US federal government’s list of known carcinogens (US Department of Health and Human Services, 2005). Several HCAs also occur in tobacco smoke and diesel exhaust. HCAs were first discovered in cooked foods by Professor Sugimura and colleagues more than 30 years ago (Sugimura, 1997; Sugimura et al., 2004). Since that time, more than 20 HCAs have been identified in cooked meats. PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine) is one of the most abundantly formed HCAs in cooked meat. PhIP is associated with an increased risk of cancer of the colon, breast and prostate (Wilson et al., 2007). PhIP is formed when creatine (an amino acid found in muscle) and other amino acids and sugars, which are naturally present in meats, are heated during cooking (Jagerstad et al., 1991). All meats, including white meat and fish, are high in creatine, which is mostly found in muscle tissue. Unsurprisingly, fish shows significant HCA formation. Grilled veggie burgers and other vegetarian foods such as portabello mushrooms contain either no HCAs or negligible levels (Nagao and Sugimura, 2000). Some of the highest concentrations of HCAs are found in grilled meat, especially chicken. Grilling is particularly carcinogen-forming because it involves high heat and long cooking times. On the grill, chicken produces more than ten times the amount of HCAs found in grilled beef. Chicken contains large amounts of the amino acids phenylalanine, tyrosine and isoleucine, which contribute to HCA formation. Frying and oven-baking also frequently produce large amounts of HCAs (Skog et al., 1998; Robbana- Barnat et al., 1996; Thiebaud et al., 1995). 27
  28. 28. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat The concentrations of HCAs formed in meats prepared by common household cooking practices are generally in the low parts-per-billion (ppb) range. Concentrations in meats or poultry that are well- done (Skog et al., 1998), or the grilled pan scrapings often used for gravy, can be as high as 500 ppb. However, even at low concentrations, HCAs have been shown to induce DNA damage and initiate cancer (Felton et al., 2002). DNA adducts of HCAs have been detected in human tissues. Cooked meat has been shown to contain up to 50ng PhIP per gram of meat, thus intakes of between 1 and 50 micrograms PhIP per day are feasible (in Lauber et al., 2004). PhIP consumed in meat is extensively absorbed (Boobis et al., 1994). Exactly how PhIP increases cancer risk is uncertain. It has been suggested that PhIP produces harmful molecules called reactive oxygen species which cause DNA strands to break, thus increasing cancer risk (Wilson et al., 2007). An alternative suggestion by researchers at Imperial College in London is that PhIP is a potent mimic of the hormone oestrogen (Lauber and Gooderham, 2007). Many studies link higher oestrogen levels to breast cancer (eg Ali and Coombes, 2002). Oestrogens have also linked to cancers of the ovaries (Lacey et al., 2002), endometrium (Sherman, 2000), prostate (Oh, 2002) and colon (English et al., 2001). PhIP has oestrogenic activity even at the low concentrations typically found in home cooking. Lauber et al. conclude that: “Exposure to PhIP even at low doses, could result in oestrogenic effects,” (Lauber et al., 2004). Recently a not-for-profit organisation in the USA (Physicians Committee for Responsible Medicine, or PCRM) filed a lawsuit against seven high street restaurant chains over carcinogens in grilled chicken. In independent laboratory tests by Columbia Analytical Services, 100 grilled chicken items from American restaurants including McDonalds, Burger King and TGI Friday’s were all found to contain PhIP. Every sample from every restaurant was found to contain PhIP (PCRM, 2008b). The lawsuit was filed in Los Angeles Superior Court under proposition 65, which was designed to ‘protect the health and safety of California residents’. Burger King, based in Miami, settled the lawsuit by agreeing to warn customers that its grilled chicken entrees contain PhIP. PCRM reports that warning signs have been posted in Burger King’s California restaurants (PCRM, 2008b). In addition to HCAs, cooked meats also contain a variety of carcinogens at low concentrations, including: polycyclic aromatic hydrocarbons, N-nitroso compounds, lipid peroxides, other pro- oxidative agents, and fungal products. Cross and Sinha suggest that the carcinogenic potency of grilled meats, and health risk, may be related not only to HCAs, but also to this complex mixture of genotoxic compounds (Cross and Sinha, 2004). Genotoxic compounds are chemicals which are thought to interact with DNA to cause cancer. The Food Standards Agency comments: “It isn’t possible to establish a safe level of consumption for genotoxins but independent experts advise that intakes should be as low as possible,” (Food Standards Agency, 2008d). 28
  29. 29. Polycyclic Aromatic Hydrocarbons (PAHs) When foods are grilled over a direct flame – with fat dropping down on to it – polycyclic aromatic hydrocarbons (PAHs) are contained in the flames. PAHs stick to the surface of the food: the more intense the heat, the more PAHs are present (World Cancer Research Fund, 1997). They are believed to play a significant role in human cancers (Norat and Riboli, 2001). There is a fairly consistent link between grilled (but not fried) meat consumption and stomach cancer. This implies that dietary PAHs may play a role in the development of stomach cancer (World Cancer Research Fund, 1997). While HCAs only form in meat, poultry and fish, PAHs may also be formed in other foods. PAHs are also produced when fossil fuels or refuse are burnt, and are found in tobacco smoke and vehicle exhaust emissions. Avoiding animal products – including white meat – is a key step in steering clear of HCAs, PAHs, nitrosamines, and other cancer-promoting substances. Cardiovascular Disease (CVD) Cardiovascular disease (CVD) describes conditions that affect the heart and blood vessels. It usually occurs as a result of atherosclerosis (hardening and narrowing of the arteries). Atherosclerosis starts when the blood vessels are damaged. This can occur for many reasons, such as stress, high blood pressure or even a viral or bacterial infection. The body’s response is inflammation. It sends in certain fix-it cells (white blood cells) to try to repair the damage. Over time, the white blood cells collect fatty deposits (plaques). These plaques build up on the inner artery walls, narrowing the arteries. The more cholesterol in the blood, the faster plaques grow. The plaques may eventually become so thick that they completely block the flow of blood through the arteries. Many diet and lifestyle factors can cut the risk of atherosclerosis – and therefore reduce the risk of CVD. CVD is the single largest cause of death in the UK, accounting for approximately 200,000 deaths per year. Most of these deaths result from either heart disease or strokes (NHS, 2009e). The Role of Atherosclerosis in Coronary Heart Disease The heart is a pump which circulates blood around the body. Like other muscles, it needs oxygen and other nutrients to provide the energy for its work. The coronary arteries provide this, supplying the heart with oxygen-rich blood. Coronary heart disease usually occurs as a result of atherosclerosis. Plaques in the coronary arteries reduce blood supply to the heart muscles. In some cases, plaques rupture, causing a blood clot to form. If blood flow to the heart is blocked by a blood clot a heart attack can occur. Heart attacks can be silent and painless or they can be extremely painful and deadly. Permanent damage to the heart can occur – in fact the affected part of the heart can die. In the following weeks 29
  30. 30. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat this dead muscle is replaced by scar tissue. Unlike the rest of the heart, scar tissue cannot contract, which makes the heart work less efficiently. Coronary heart disease is the UK’s biggest killer, with one in every four men and one in every six women dying from the disease. In the UK, approximately 300,000 people have a heart attack each year (NHS, 2009f). With angina, the blood vessels supplying the heart are partially, rather than fully, blocked by atherosclerosis. This reduced capacity allows enough blood to the heart when a person is resting but not enough to provide sufficient oxygen for physical activity. This can lead to discomfort or severe chest pain. The pain may also occur in the shoulders, arms, neck, jaw or back or feel like indigestion. There is also sometimes difficulty in breathing, weakness, sweating, fear of death, nausea, numbness or tingling in the arms or fingers. In some cases there are no symptoms at all. Angina affects about one in 50 people, and in the UK there are an estimated 1.2 million people with the condition. It affects men more than women, and the chances of getting it increase with age (NHS, 2009f). White Meat Consumption and Cardiovascular Disease Risk A large recent study shows that white meat intake increases the risk of death from cardiovascular disease in men, and in both male and female non-smokers. National Cancer Institute researchers investigated the diets of approximately half a million people aged 50 to 71. They examined the relationship between red, white, and processed meat intake and mortality. Among those who had never smoked, higher white meat intake was associated with increased cardiovascular disease mortality. This was true for both men and women. Surprisingly, given all of the other evidence to the contrary (see Cancer, page 21, and HCAs, page 27) the study also reported a link with higher white meat intake and reduced cancer mortality (Sinha et al., 2009). With all heart-related diseases, vegetarians suffer less than meat eaters and the more meat you eat, the more likely you are to end up with atherosclerosis. According to the WHO’s report on diet, nutrition and disease published in 1991, dietary factors clearly play a role in CVD: “All the available evidence suggests that, for cardiovascular disease and cancer, diet has an influence throughout the life cycle, even though the end-points are manifested in the adult,” (World Health Organisation, 1991). After 30 years of surgery, world renowned heart surgeon Christiaan Barnard concluded that most heart attacks are preventable. He states that our diets lack sufficient fruits and vegetables, are not properly balanced and that we should live like the people of Crete, where heart disease is almost unknown. Fruit and vegetables are the mainstay of the diet and meat consumption is 32 per cent less than in northern Europe (Barnard, 2001). Many of the countries performing best in terms of health are characterised by such diets (Evans et al., 2001; McKee, 2001). A well-balanced vegetarian diet is by its very nature along the lines of a Mediterranean-type diet – with higher intakes of plant foods, especially fruits and vegetables, and of course zero meat consumption. 30
  31. 31. A number of studies have demonstrated that a vegetarian diet can cut the risk of heart disease (Key et al., 1998; Key et al., 1999). Compared with non-vegetarians, Western vegetarians were found to have lower blood cholesterol levels and lower mortality from heart disease by about 25 per cent. The widespread adoption of a vegetarian diet could prevent approximately 40,000 deaths from heart disease in the UK each year (Key et al., 1999). Apart from being slimmer, having lower cholesterol levels and lower blood pressure levels, research suggests yet another factor may protect vegetarians against heart disease. Scottish researchers found that levels of salicylic acid in the blood of vegetarians were up to one-and-a-half times higher than in meat eaters. Some vegetarians had levels up to 12 times higher (Blacklock et al., 2001). Salicylic acid is the main component of aspirin – widely prescribed to reduce the risk of heart attacks – which helps fight the inflammation that causes most cardiovascular illness. Salicylic acid is also present in fruits and vegetables suggesting a high dietary intake may produce some of the same good effects as aspirin. Dr Dean Ornish Back in 1990, Dr Dean Ornish, a Harvard-trained doctor, published a study that set out to test whether heart disease could not only be prevented, but might also actually be reversed. He wanted to see whether it could be done with diet and lifestyle changes alone rather than surgery or drugs. Before then, most doctors did not even attempt to reverse heart disease even though, as now, it was a major cause of death. Most believed that the plaques of cholesterol and other substances that clog arteries to the heart could not be reduced. The traditional way to remove them was to wait until they became severe enough to warrant a bypass or angioplasty. Dr Ornish studied 47 patients in the San Francisco Bay Area, all of whom had significant heart disease with some already having had heart attacks. One group of heart patients was given the standard care that doctors usually prescribe – a diet based on ‘lean’ meat, poultry and fish, along with various medications, and were advised not to smoke. Another group went on a low-fat, vegetarian diet (less than 10 per cent of their calories from fat) exercised moderately (brisk walking for half an hour per day or an hour three times per week), were taught stress management and were also advised not to smoke. A year later, all patients had an angiogram – an X-ray showing any blockages in the coronary arteries. The results were astonishing. For the patients receiving standard medical care, blockages were, on average, worse than at the start of the study; they still had chest pain and still needed medication. For patients in the experimental group, however, the story was very different. Chest pain had begun to disappear within weeks, cholesterol levels dropped dramatically and at the end of the year, 82 per cent saw deposits (plaques) in their coronary arteries start to dissolve without medication, surgery or side effects! The only ‘side effects’ were good ones – the average patient lost around one-and-a-half stones in the first year! Many doctors still recommend ‘chicken and fish’ diets even though numerous studies have shown that heart patients who just tinker with their diets in this way generally get worse over time. Those who 31
  32. 32. white meat black mark The health consequences of consuming chicken, turkey, duck and goose meat adopt a low-fat, vegetarian diet, take daily exercise, avoid tobacco and manage stress stand the best chance of reversing heart disease. Dr Caldwell Esselstyn A surgeon named Dr Caldwell Esselstyn used the same type of diet for severely ill heart patients, the majority of whom had, in effect, received a death sentence. Doctors had told them there was nothing more they could do and some had been given less than a year to live. Just about everything had been tried – repeated open heart surgery, angioplasties, stents and a plethora of medications. There was no longer any useful effect and almost all the men were impotent, most had angina and for some, things were so bad that they couldn’t lie down and had to sleep sitting up. Having completely run out of options they agreed to the demanding conditions Dr Esselstyn set for entry into the trial cure he had come to believe in. They agreed to join him in a diet not unlike two- thirds of the world’s population (outside the West) – a low-fat, plant-based diet. Of the patients who stuck to Dr Esselstyn’s programme, there was not a single cardiac event over the next 12 years! All were alive and well and had reversed their disease. Dr Esselstyn has since gone on to counsel and treat many more patients. The Effect of White Meat on Cholesterol Cholesterol is a type of lipid (fat) called a sterol made by the liver and present in every cell in an animal’s body, including human animals. It is found only in foods of animal origin – white meat, fish, eggs, and every other meat and dairy product. Foods from plants (all types of fruits and vegetables, pulses (peas, beans and lentils), wholegrains, nuts and seeds) are cholesterol-free. The liver makes all the cholesterol we need – approximately 1,000 milligrams per day – used in the manufacture of hormones and cell membranes, and in other parts of the body. This means that people have no dietary need for cholesterol at all. Cholesterol cannot be avoided by choosing lean cuts of meat, as cholesterol is mainly found in the lean portion. Neither is white meat lower in cholesterol than red meat – chicken contains as much cholesterol as beef (Pennington, 1989). One small grilled skinless chicken breast contains around 100 milligrams of cholesterol (Food Standards Agency, 2002). Just this amount of cholesterol in your daily diet adds roughly 0.13 mmol/L (or 5 mg/dL) to your cholesterol level, although this varies from person to person. The American Heart Association recommends that people limit their average daily cholesterol intake to no more than 300 milligrams (AHA, 2008). When cholesterol is transported in the bloodstream, it is packed into low-density lipoproteins (LDL), sometimes called ‘bad cholesterol’. Although LDL is necessary in limited quantities (to deliver cholesterol to various parts of the body), a high LDL cholesterol level can dramatically increase heart attack risk. 32
  33. 33. When cholesterol is released from dead cells, it is picked up for disposal in another kind of package, called high-density lipoproteins (HDL), or ‘good cholesterol’. The lower your total cholesterol level, and the higher your HDL as a proportion of this, the lower your risk of a heart attack. The ratio of total cholesterol to HDL should, ideally, be less than 4 to 1. Vegetarians average at about 2.8 to 1.3 – much lower than the average Westerner (PCRM, 2009c). Vegetarians have consistently been found to have lower levels of both serum total and LDL cholesterol. This would perhaps be expected because their intakes of saturated fat and cholesterol are lower, and intakes of dietary fibre, phytosterols, and, sometimes, polyunsaturated fat are higher. All of these factors favourably affect serum LDL cholesterol levels (Howard and Kritchevsky, 1997; Van Horn, 1997). Some of these studies have been observational in design, comparing a group of vegetarians with a group of non-vegetarians (they are usually matched by age, sex, and other factors) – for example, Appleby et al., 1995. There is always a concern that factors aside from diet will differ among vegetarians and omnivores – and that these may be the cause of any lipid differences. However, if the groups are well matched, evidence of a dietary effect on blood lipids can be strong. West and Hayes (1968) compared 233 Adventist non-vegetarians with 233 Adventist vegetarians in Washington DC. The participants were matched by the specific church they attended, sex, age (within five years), marital status, height, weight and occupation. The non-vegetarians were grouped into four categories ranging from those who ate meat less than once each month through to those eating meat more than three times weekly. Those who ate meat just once a week or more had blood cholesterol levels that were, on average 19 mg/dL (approximately 0.5mmol/L) higher than those for the vegetarians. Lipid levels were also compared among 1,344 meat-eaters (more than once per week), 136 fish-eaters (fish, but not meat, more than once per week), 374 semi-vegetarians (meat or fish less than once per week), 1,785 strict vegetarians (but excluding vegans), and 134 vegans (who ate no animal products) in the Oxford Vegetarian Study (Appleby et al., 1995). Total cholesterol levels were significantly lower in all non-meat-eating categories, but particularly so for vegans, where the difference was 16 per cent to 18 per cent. In an attempt to isolate the effect of meat, the investigators adjusted for the other significant dietary factors that were also related to blood lipid levels – such as dietary fibre and cheese (for men), type of fat spread, dietary fibre, and tomatoes (for women). On average eating meat at least five times weekly raised serum total cholesterol by 8.6 per cent in men and 8.8 per cent in women. Low-fat, vegetarian diets, devoid of all meat, can bring cholesterol down by up to 32 per cent. When lean meat was substituted by soya bean curd (tofu), again levels fell considerably (Ashton et al., 2000). Animal products also contain saturated fat, which causes the liver to produce more cholesterol (see Saturated Fat, page 9). Unsaturated fats do not have this effect. 33